This invention relates generally to a matrix display panel of the type using liquid crystal elements and more particularly to a driving circuit for a matrix display panel which improves picture quality by reducing the number of lines of data used in producing the image.
A matrix display panel, wherein driving electrodes are arranged in a matrix in both the X and Y directions, is used for displaying letters, graphs and images. For example, in a liquid crystal display panel there are n.times.m picture elements or pieces, which are arranged to form n data lines and m scanning lines. In a conventional method of the prior art, the liquid crystal display panel is driven with multiplexed signals, namely one scanning line is selected and then data signals, provided on n data lines, are written into the respective picture elements of the scanning line. The period for applying the corresponding data to one picture element becomes 1/m of the entire period for driving the matrix and this is generally called "duty" (duty cycle). Generally speaking, at least 100 scanning lines are required for displaying pictures or graphs. When displaying images which require contrast in the gray scale, video signals are applied to the picture elements, for example, by modulating the width of the driving pulse in accordance with the gray scale levels.
In the case of television signals, there are 525 scanning lines in one frame and each frame is divided into an odd numbered field and an even numbered field by interlacing 262.5 scanning lines in each field. Accordingly, when displaying an image on the liquid crystal matrix panel with such television signals, the panel must be driven in 1/2.62.5 duty if every scanning line is to be applied to the matrix. Even when reducing image resolution to half, the matrix display panel must be driven with 1/131.25 duty. However, there is a disadvantage in driving a liquid crystal display panel at such a high duty in that the image contrast is not satisfactory.
What is needed is a simplified liquid crystal matrix display panel suitable for showing images requiring a high number of lines, for example, television images, with good contrast and resolution.